Re: [Bug 1902470] Re: migration with TLS-MultiFD is stuck when the dst-libvirtd service restarts

[Zheng Chuan]

On 2020/11/3 17:29, Daniel Berrange wrote:
> This looks to me like a significant implementation flaw in the QEMU
> code. Both src and dst QEMU appear to be running code from the main
> event loop, and they appear to be doing blocking I/O operations. This is
> very bad as we should never have anything running in the main event loop
> thread that is able to block on I/O.
> 
Well, the tls handshake seems to be blocking I/O.

> So to solve this something needs to be done to make sure the I/O is
> either non-blocking, or if it has to be blocking, then it needs to be
> offloaded to a background thread.
> 
Yes, i agree.
Since we do multifd tls handshake in main thread through multifd_save_setup(), 
maybe
we need to make socket_send_channel_create() to be a background thread other
than qio_channel_socket_connect_async()?

Besides，the hang problem itself still need to be figured out and solved...

-- 
Regards.
Chuan